Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi LawrencePyle,
May I know the email address you received the non-delivery report (error) is Office 365 for Business account? Since based on my understanding, it's an error bounced back from Office 365. You can provide the entire NDR to us in PM as my first reply for further check. If you are not using Office 365 for Business account, you can contact your mail service provider to check this for you.
Thanks,
Iry